This invention relates generally to lawn and garden tractors and, more particularly, to mower decks for lawn and garden tractors.
To reduce the time needed to mow a lawn, mower decks for lawn and garden tractors should be relatively wide from side to side. However, to reduce vehicle length, such decks should be relatively narrow from front to back. To satisfy both these requirements, various known mower decks include two blades in side-by-side relation.
When two side-by-side blades are used, some provision should be made to ensure that the swaths cut by each blade overlap. This avoids leaving a strip of uncut grass between the blades. Various overlap systems have been developed for two bladed mower decks.
In one common arrangement, two equal size blades are offset slightly front to back. By placing one blade slightly ahead of the other along the direction of travel, each blade cuts a swath that overlaps, slightly, the swath cut by the other blade. Such a "tangent overlap" system is effective when the tractor is moving straight ahead, but can break down during turns when the relative direction of movement is along a path extending between the blades. In addition, placing one blade ahead of the other increases the front to back dimension of the mower deck.
Another overlap system calls for orienting the blades so that the rotational paths or circles described by the blade tips physically overlap. In such a "blade overlap" system, the blades must be timed or synchronized to avoid their hitting each other. This calls for relatively complicated and expensive gearing and can be dangerous if the blades somehow become unsynchronized.
Still another overlap system calls for the addition of a third, smaller blade positioned behind and between the two main blades. The main blades are spaced sufficiently apart to prevent their hitting, and the small third blade cuts the grass missed by the two main blades. Although effective, the addition of another blade increases complexity, expense and complicates routine maintenance.
To further increase the utility of a mower deck, some provision should be made for adjusting cutter height. In the past, cutter height was adjusted by setting the mower deck support wheels or rollers to one of several discreet height settings. To permit a wide range of adjustment, several of the discreet settings were required. This increased the cost and complexity of the mower deck. In addition, because of the discreet height adjustment steps, it was impossible in some circumstances to achieve the optimum cutting height.
In view of the foregoing, it is a general object of the present invention to provide a new and improved two-blade mower deck.
It is a further object of the present invention to provide a new and improved mower deck that provides reliable and effective mowing path overlap in a variety of cutting conditions.
It is a still further object of the present invention to provide a new and improved mower deck that is simple, reliable and economical in manufacture.
It is a still further object of the present invention to provide a new and improved mower deck that allows infinitely variable adjustment of the cutting height.